Build: Switch licenses to license to silence npm warnings

The "licenses" field is deprecated.

Author: mgol

package.json

@@ -13,12 +13,7 @@
   "bugs": {
     "url": "https://github.com/jquery/codeorigin.jquery.com/issues"
   },
-  "licenses": [
-    {
-      "type": "MIT",
-      "url": "https://github.com/jquery/codeorigin.jquery.com/blob/master/LICENSE.txt"
-    }
-  ],
+  "license": "MIT",
   "dependencies": {
     "grunt": "0.4.5",
     "grunt-cli": "0.1.13",